package com.clark.io;

import java.io.File;
import java.io.Serializable;

/**
 * Filters files based on size, can filter either smaller files or files equal
 * to or larger than a given threshold.
 * <p>
 * For example, to print all files and directories in the current directory
 * whose size is greater than 1 MB:
 * 
 * <pre>
 * File dir = new File(&quot;.&quot;);
 * String[] files = dir.list(new SizeFileFilter(1024 * 1024));
 * for (int i = 0; i &lt; files.length; i++) {
 *     System.out.println(files[i]);
 * }
 * </pre>
 * 
 * @author Rahul Akolkar
 * @version $Id: SizeFileFilter.java 1005099 2010-10-06 16:13:01Z niallp $
 * @since Commons IO 1.2
 * @see FileFilterUtils#sizeFileFilter(long)
 * @see FileFilterUtils#sizeFileFilter(long, boolean)
 * @see FileFilterUtils#sizeRangeFileFilter(long, long)
 */
public class SizeFileFilter extends AbstractFileFilter implements Serializable {

    private static final long serialVersionUID = -6642204383456026127L;
    /** The size threshold. */
    private final long size;
    /** Whether the files accepted will be larger or smaller. */
    private final boolean acceptLarger;

    /**
     * Constructs a new size file filter for files equal to or larger than a
     * certain size.
     * 
     * @param size
     *            the threshold size of the files
     * @throws IllegalArgumentException
     *             if the size is negative
     */
    public SizeFileFilter(long size) {
        this(size, true);
    }

    /**
     * Constructs a new size file filter for files based on a certain size
     * threshold.
     * 
     * @param size
     *            the threshold size of the files
     * @param acceptLarger
     *            if true, files equal to or larger are accepted, otherwise
     *            smaller ones (but not equal to)
     * @throws IllegalArgumentException
     *             if the size is negative
     */
    public SizeFileFilter(long size, boolean acceptLarger) {
        if (size < 0) {
            throw new IllegalArgumentException("The size must be non-negative");
        }
        this.size = size;
        this.acceptLarger = acceptLarger;
    }

    // -----------------------------------------------------------------------
    /**
     * Checks to see if the size of the file is favorable.
     * <p>
     * If size equals threshold and smaller files are required, file <b>IS
     * NOT</b> selected. If size equals threshold and larger files are required,
     * file <b>IS</b> selected.
     * 
     * @param file
     *            the File to check
     * @return true if the filename matches
     */
    @Override
    public boolean accept(File file) {
        boolean smaller = file.length() < size;
        return acceptLarger ? !smaller : smaller;
    }

    /**
     * Provide a String representaion of this file filter.
     * 
     * @return a String representaion
     */
    @Override
    public String toString() {
        String condition = acceptLarger ? ">=" : "<";
        return super.toString() + "(" + condition + size + ")";
    }

}
